It hopes to be able to expand the scheme to make it available to customers later this year.

Once the app is downloaded, users need to complete their profile details and can then start to make payments. It connects to Apple Pay, where users can confirm payments securely using Touch ID. It lets users transfer between £10 and £10,000 and payments can be made from pounds to euros and US dollars.

The app uses blockchain technology, which facilitates international payments. The blockchain network enables virtual currencies to pass through from sender to receiver. Santander said for banks, blockchain can enable the transfer of data in a faster and more accurate way.

The blockchain technology underpinning the app is provided by the company Ripple.

Santander said at present, timescales can vary for international transactions and some can take several days to go through.

It said the technology it is using validates the transfer up-front, unlike some other transfer providers, where the money may be cleared through a range of systems and processes. Santander said the new app gives users the comfort of knowing that the payment they send will arrive the next working day.

Sigga Sigurdardottir, head of customer and innovation at Santander said: "The need for finance has evolved from providing a physical pound in your pocket or card in your purse, where you pay at a till, to being seamlessly integrated into a new, always-on, connected lifestyle."